Abstract: The Arctic is undergoing widespread warming. In order to understand the impact of climate change on Arctic marine food webs, we studied the at-sea distribution of foraging little auks in contrasting conditions of the Greenland Sea. While the eastern side of the Greenland Sea has experienced recent warming, the western side is still dominated by cold, Arctic water in the East Greenland Current. We hypothesized that foraging little auks would be found in greatest abundance in cold Arctic waters bearing more lipid-rich prey, allowing them to deliver more energy-rich food to their chicks. To test our hypotheses, we made ship-borne bird observations and zooplankton tows, as well as analyses of chick meals at 2 little auk colonies adjacent to 3 distinct water masses in the Greenland Sea. Associated with the coldest water in the East Greenland Current, we found the highest concentrations of large Calanus copepods (C. glacialis and C. hyperboreus), as well as the highest concentrations of foraging little auks, indicating a relationship that is likely to be disrupted by increasing water temperatures. To assess potential future impacts of ocean warming, we used a coupled atmosphere–ocean global climate model (AOGCM) to predict Greenland Sea sea-surface temperatures over the study area at the end of the 21st century. Our results suggest that 4 of 8 little auk breeding colonies in the North Atlantic may be negatively impacted as temperatures exceed the thermal preferenda of large Calanus, which is the preferred prey of little auks during the breeding season.

Abstract: In this review we detail the impact of climate change on marine productivity, on marine environmental stochasticity and cyclicity, and on the spatio-temporal match-mismatch of seabirds and their prey. We thereby show that global warming has a profound bottom-up impact upon marine top-predators, but that such effects have to be studied in conjunction with the (top-down) impact of human fisheries upon seabird food resources. Further, we propose seabird ecological features, such as memory effects and social constraints, that make them particularly sensitive to rapid environmental change. We provide examples of how seabirds may nonetheless adapt when facing the consequences of climate change. We conclude that our understanding of the spatial ecology of seabirds facing environmental change is still rudimentary, despite its relevance for the conservation of these vulnerable organisms and for the management of marine ecosystems. We define the following research priorities. (1) Determine the factors affecting seabird distribution and movements at sea using biotelemetry, as well as colony dynamics on land. (2) Link seabird distribution patterns to those of their prey, (3) Determine further the role of historical and metapopulation processes in contributing to the dynamics of the spatial distribution of seabirds. (4) Assess phenotypic plasticity and the potential for microevolution within seabird spatial responses to climate change, since both will greatly affect the quality of modelling studies. (5) Adapt existing models to define and predict the impact of climate change onto seabird spatial dynamics. (6) Synthesize all gathered information to define marine protected areas and further conservation schemes, such as capacity reduction of fisheries. This research effort will require maintaining existing long-term monitoring programmes for seabirds, as well as developing new approaches to permit the integration of processes occurring at various scales, in order to be able to fully track the population responses of these long-lived vertebrates to environmental changes.